This invention relates to hydrogenation processes. In one of its aspects this invention relates to the hydrogenation of unsaturated diesters. In another of its aspects this invention relates to the suppression of side reactions in the hydrogenation of unsaturated diesters. In yet another aspect of the invention it relates to modifying agents for catalytic reactions. In yet another aspect of the invention it relates to the suppression of hydrogenolysis of a diester to the monoester.
The use of polyesters in manufacturing has grown considerably in recent years. With the growth of use of polyesters the means for producing glycols or diols from which polyesters can be formed have also become more important. One method for producing diols is the production of unsaturated diesters, such as those made by the reaction of conjugated diolefins with monocarboxylic acids, with subsequent hydrogenation to produce saturated diesters which upon treatment with an hydroxide yields a diol.
Unfortunately, when this route is taken for producing diols the hydrogenation of the unsaturated diester, although usually proceeding smoothly, is accompanied by a side reaction that is a hydrogenolysis which splits off one of the ester groups to leave a monoester. Since in the production of a diol it is important to produce as high yield of saturated diester as possible, the side reaction should be kept to a minimum. It has now been discovered that the hydrogenolysis can be suppressed by the addition of certain compounds to the reaction mixture in the hydrogenation.
It is therefore an object of this invention to provide a method for hydrogenating unsaturated diesters. It is a more specific object of this invention to provide a method for hydrogenating unsaturated diesters which are made by the reaction of conjugated diolefins with monocarboxylic acids. It is another object of this invention to provide a method for suppressing side reactions, specifically hydrogenolysis, in the hydrogenation of unsaturated diesters.
Other aspects, objects, and the various advantages of this invention will become apparent upon studying the specification and appended claims.